Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

1868 lines (1641 sloc) 53.858 kb
/*
* mm/kmemleak.c
*
* Copyright (C) 2008 ARM Limited
* Written by Catalin Marinas <catalin.marinas@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*
* For more information on the algorithm and kmemleak usage, please see
* Documentation/kmemleak.txt.
*
* Notes on locking
* ----------------
*
* The following locks and mutexes are used by kmemleak:
*
* - kmemleak_lock (rwlock): protects the object_list modifications and
* accesses to the object_tree_root. The object_list is the main list
* holding the metadata (struct kmemleak_object) for the allocated memory
* blocks. The object_tree_root is a priority search tree used to look-up
* metadata based on a pointer to the corresponding memory block. The
* kmemleak_object structures are added to the object_list and
* object_tree_root in the create_object() function called from the
* kmemleak_alloc() callback and removed in delete_object() called from the
* kmemleak_free() callback
* - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
* the metadata (e.g. count) are protected by this lock. Note that some
* members of this structure may be protected by other means (atomic or
* kmemleak_lock). This lock is also held when scanning the corresponding
* memory block to avoid the kernel freeing it via the kmemleak_free()
* callback. This is less heavyweight than holding a global lock like
* kmemleak_lock during scanning
* - scan_mutex (mutex): ensures that only one thread may scan the memory for
* unreferenced objects at a time. The gray_list contains the objects which
* are already referenced or marked as false positives and need to be
* scanned. This list is only modified during a scanning episode when the
* scan_mutex is held. At the end of a scan, the gray_list is always empty.
* Note that the kmemleak_object.use_count is incremented when an object is
* added to the gray_list and therefore cannot be freed. This mutex also
* prevents multiple users of the "kmemleak" debugfs file together with
* modifications to the memory scanning parameters including the scan_thread
* pointer
*
* The kmemleak_object structures have a use_count incremented or decremented
* using the get_object()/put_object() functions. When the use_count becomes
* 0, this count can no longer be incremented and put_object() schedules the
* kmemleak_object freeing via an RCU callback. All calls to the get_object()
* function must be protected by rcu_read_lock() to avoid accessing a freed
* structure.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/jiffies.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/kthread.h>
#include <linux/prio_tree.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/cpumask.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include <linux/stacktrace.h>
#include <linux/cache.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
#include <linux/mmzone.h>
#include <linux/slab.h>
#include <linux/thread_info.h>
#include <linux/err.h>
#include <linux/uaccess.h>
#include <linux/string.h>
#include <linux/nodemask.h>
#include <linux/mm.h>
#include <linux/workqueue.h>
#include <linux/crc32.h>
#include <asm/sections.h>
#include <asm/processor.h>
#include <linux/atomic.h>
#include <linux/kmemcheck.h>
#include <linux/kmemleak.h>
#include <linux/memory_hotplug.h>
/*
* Kmemleak configuration and common defines.
*/
#define MAX_TRACE 16 /* stack trace length */
#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
#define SECS_FIRST_SCAN 60 /* delay before the first scan */
#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
#define BYTES_PER_POINTER sizeof(void *)
/* GFP bitmask for kmemleak internal allocations */
#define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
__GFP_NORETRY | __GFP_NOMEMALLOC | \
__GFP_NOWARN)
/* scanning area inside a memory block */
struct kmemleak_scan_area {
struct hlist_node node;
unsigned long start;
size_t size;
};
#define KMEMLEAK_GREY 0
#define KMEMLEAK_BLACK -1
/*
* Structure holding the metadata for each allocated memory block.
* Modifications to such objects should be made while holding the
* object->lock. Insertions or deletions from object_list, gray_list or
* tree_node are already protected by the corresponding locks or mutex (see
* the notes on locking above). These objects are reference-counted
* (use_count) and freed using the RCU mechanism.
*/
struct kmemleak_object {
spinlock_t lock;
unsigned long flags; /* object status flags */
struct list_head object_list;
struct list_head gray_list;
struct prio_tree_node tree_node;
struct rcu_head rcu; /* object_list lockless traversal */
/* object usage count; object freed when use_count == 0 */
atomic_t use_count;
unsigned long pointer;
size_t size;
/* minimum number of a pointers found before it is considered leak */
int min_count;
/* the total number of pointers found pointing to this object */
int count;
/* checksum for detecting modified objects */
u32 checksum;
/* memory ranges to be scanned inside an object (empty for all) */
struct hlist_head area_list;
unsigned long trace[MAX_TRACE];
unsigned int trace_len;
unsigned long jiffies; /* creation timestamp */
pid_t pid; /* pid of the current task */
char comm[TASK_COMM_LEN]; /* executable name */
};
/* flag representing the memory block allocation status */
#define OBJECT_ALLOCATED (1 << 0)
/* flag set after the first reporting of an unreference object */
#define OBJECT_REPORTED (1 << 1)
/* flag set to not scan the object */
#define OBJECT_NO_SCAN (1 << 2)
/* number of bytes to print per line; must be 16 or 32 */
#define HEX_ROW_SIZE 16
/* number of bytes to print at a time (1, 2, 4, 8) */
#define HEX_GROUP_SIZE 1
/* include ASCII after the hex output */
#define HEX_ASCII 1
/* max number of lines to be printed */
#define HEX_MAX_LINES 2
/* the list of all allocated objects */
static LIST_HEAD(object_list);
/* the list of gray-colored objects (see color_gray comment below) */
static LIST_HEAD(gray_list);
/* prio search tree for object boundaries */
static struct prio_tree_root object_tree_root;
/* rw_lock protecting the access to object_list and prio_tree_root */
static DEFINE_RWLOCK(kmemleak_lock);
/* allocation caches for kmemleak internal data */
static struct kmem_cache *object_cache;
static struct kmem_cache *scan_area_cache;
/* set if tracing memory operations is enabled */
static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
/* set in the late_initcall if there were no errors */
static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
/* enables or disables early logging of the memory operations */
static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
/* set if a kmemleak warning was issued */
static atomic_t kmemleak_warning = ATOMIC_INIT(0);
/* set if a fatal kmemleak error has occurred */
static atomic_t kmemleak_error = ATOMIC_INIT(0);
/* minimum and maximum address that may be valid pointers */
static unsigned long min_addr = ULONG_MAX;
static unsigned long max_addr;
static struct task_struct *scan_thread;
/* used to avoid reporting of recently allocated objects */
static unsigned long jiffies_min_age;
static unsigned long jiffies_last_scan;
/* delay between automatic memory scannings */
static signed long jiffies_scan_wait;
/* enables or disables the task stacks scanning */
static int kmemleak_stack_scan = 1;
/* protects the memory scanning, parameters and debug/kmemleak file access */
static DEFINE_MUTEX(scan_mutex);
/* setting kmemleak=on, will set this var, skipping the disable */
static int kmemleak_skip_disable;
/*
* Early object allocation/freeing logging. Kmemleak is initialized after the
* kernel allocator. However, both the kernel allocator and kmemleak may
* allocate memory blocks which need to be tracked. Kmemleak defines an
* arbitrary buffer to hold the allocation/freeing information before it is
* fully initialized.
*/
/* kmemleak operation type for early logging */
enum {
KMEMLEAK_ALLOC,
KMEMLEAK_ALLOC_PERCPU,
KMEMLEAK_FREE,
KMEMLEAK_FREE_PART,
KMEMLEAK_FREE_PERCPU,
KMEMLEAK_NOT_LEAK,
KMEMLEAK_IGNORE,
KMEMLEAK_SCAN_AREA,
KMEMLEAK_NO_SCAN
};
/*
* Structure holding the information passed to kmemleak callbacks during the
* early logging.
*/
struct early_log {
int op_type; /* kmemleak operation type */
const void *ptr; /* allocated/freed memory block */
size_t size; /* memory block size */
int min_count; /* minimum reference count */
unsigned long trace[MAX_TRACE]; /* stack trace */
unsigned int trace_len; /* stack trace length */
};
/* early logging buffer and current position */
static struct early_log
early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
static int crt_early_log __initdata;
static void kmemleak_disable(void);
/*
* Print a warning and dump the stack trace.
*/
#define kmemleak_warn(x...) do { \
pr_warning(x); \
dump_stack(); \
atomic_set(&kmemleak_warning, 1); \
} while (0)
/*
* Macro invoked when a serious kmemleak condition occurred and cannot be
* recovered from. Kmemleak will be disabled and further allocation/freeing
* tracing no longer available.
*/
#define kmemleak_stop(x...) do { \
kmemleak_warn(x); \
kmemleak_disable(); \
} while (0)
/*
* Printing of the objects hex dump to the seq file. The number of lines to be
* printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
* actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
* with the object->lock held.
*/
static void hex_dump_object(struct seq_file *seq,
struct kmemleak_object *object)
{
const u8 *ptr = (const u8 *)object->pointer;
int i, len, remaining;
unsigned char linebuf[HEX_ROW_SIZE * 5];
/* limit the number of lines to HEX_MAX_LINES */
remaining = len =
min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
seq_printf(seq, " hex dump (first %d bytes):\n", len);
for (i = 0; i < len; i += HEX_ROW_SIZE) {
int linelen = min(remaining, HEX_ROW_SIZE);
remaining -= HEX_ROW_SIZE;
hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
HEX_ASCII);
seq_printf(seq, " %s\n", linebuf);
}
}
/*
* Object colors, encoded with count and min_count:
* - white - orphan object, not enough references to it (count < min_count)
* - gray - not orphan, not marked as false positive (min_count == 0) or
* sufficient references to it (count >= min_count)
* - black - ignore, it doesn't contain references (e.g. text section)
* (min_count == -1). No function defined for this color.
* Newly created objects don't have any color assigned (object->count == -1)
* before the next memory scan when they become white.
*/
static bool color_white(const struct kmemleak_object *object)
{
return object->count != KMEMLEAK_BLACK &&
object->count < object->min_count;
}
static bool color_gray(const struct kmemleak_object *object)
{
return object->min_count != KMEMLEAK_BLACK &&
object->count >= object->min_count;
}
/*
* Objects are considered unreferenced only if their color is white, they have
* not be deleted and have a minimum age to avoid false positives caused by
* pointers temporarily stored in CPU registers.
*/
static bool unreferenced_object(struct kmemleak_object *object)
{
return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
time_before_eq(object->jiffies + jiffies_min_age,
jiffies_last_scan);
}
/*
* Printing of the unreferenced objects information to the seq file. The
* print_unreferenced function must be called with the object->lock held.
*/
static void print_unreferenced(struct seq_file *seq,
struct kmemleak_object *object)
{
int i;
unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
object->pointer, object->size);
seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
object->comm, object->pid, object->jiffies,
msecs_age / 1000, msecs_age % 1000);
hex_dump_object(seq, object);
seq_printf(seq, " backtrace:\n");
for (i = 0; i < object->trace_len; i++) {
void *ptr = (void *)object->trace[i];
seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
}
}
/*
* Print the kmemleak_object information. This function is used mainly for
* debugging special cases when kmemleak operations. It must be called with
* the object->lock held.
*/
static void dump_object_info(struct kmemleak_object *object)
{
struct stack_trace trace;
trace.nr_entries = object->trace_len;
trace.entries = object->trace;
pr_notice("Object 0x%08lx (size %zu):\n",
object->tree_node.start, object->size);
pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
object->comm, object->pid, object->jiffies);
pr_notice(" min_count = %d\n", object->min_count);
pr_notice(" count = %d\n", object->count);
pr_notice(" flags = 0x%lx\n", object->flags);
pr_notice(" checksum = %d\n", object->checksum);
pr_notice(" backtrace:\n");
print_stack_trace(&trace, 4);
}
/*
* Look-up a memory block metadata (kmemleak_object) in the priority search
* tree based on a pointer value. If alias is 0, only values pointing to the
* beginning of the memory block are allowed. The kmemleak_lock must be held
* when calling this function.
*/
static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
{
struct prio_tree_node *node;
struct prio_tree_iter iter;
struct kmemleak_object *object;
prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
node = prio_tree_next(&iter);
if (node) {
object = prio_tree_entry(node, struct kmemleak_object,
tree_node);
if (!alias && object->pointer != ptr) {
kmemleak_warn("Found object by alias at 0x%08lx\n",
ptr);
dump_object_info(object);
object = NULL;
}
} else
object = NULL;
return object;
}
/*
* Increment the object use_count. Return 1 if successful or 0 otherwise. Note
* that once an object's use_count reached 0, the RCU freeing was already
* registered and the object should no longer be used. This function must be
* called under the protection of rcu_read_lock().
*/
static int get_object(struct kmemleak_object *object)
{
return atomic_inc_not_zero(&object->use_count);
}
/*
* RCU callback to free a kmemleak_object.
*/
static void free_object_rcu(struct rcu_head *rcu)
{
struct hlist_node *elem, *tmp;
struct kmemleak_scan_area *area;
struct kmemleak_object *object =
container_of(rcu, struct kmemleak_object, rcu);
/*
* Once use_count is 0 (guaranteed by put_object), there is no other
* code accessing this object, hence no need for locking.
*/
hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
hlist_del(elem);
kmem_cache_free(scan_area_cache, area);
}
kmem_cache_free(object_cache, object);
}
/*
* Decrement the object use_count. Once the count is 0, free the object using
* an RCU callback. Since put_object() may be called via the kmemleak_free() ->
* delete_object() path, the delayed RCU freeing ensures that there is no
* recursive call to the kernel allocator. Lock-less RCU object_list traversal
* is also possible.
*/
static void put_object(struct kmemleak_object *object)
{
if (!atomic_dec_and_test(&object->use_count))
return;
/* should only get here after delete_object was called */
WARN_ON(object->flags & OBJECT_ALLOCATED);
call_rcu(&object->rcu, free_object_rcu);
}
/*
* Look up an object in the prio search tree and increase its use_count.
*/
static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
{
unsigned long flags;
struct kmemleak_object *object = NULL;
rcu_read_lock();
read_lock_irqsave(&kmemleak_lock, flags);
if (ptr >= min_addr && ptr < max_addr)
object = lookup_object(ptr, alias);
read_unlock_irqrestore(&kmemleak_lock, flags);
/* check whether the object is still available */
if (object && !get_object(object))
object = NULL;
rcu_read_unlock();
return object;
}
/*
* Save stack trace to the given array of MAX_TRACE size.
*/
static int __save_stack_trace(unsigned long *trace)
{
struct stack_trace stack_trace;
stack_trace.max_entries = MAX_TRACE;
stack_trace.nr_entries = 0;
stack_trace.entries = trace;
stack_trace.skip = 2;
save_stack_trace(&stack_trace);
return stack_trace.nr_entries;
}
/*
* Create the metadata (struct kmemleak_object) corresponding to an allocated
* memory block and add it to the object_list and object_tree_root.
*/
static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
int min_count, gfp_t gfp)
{
unsigned long flags;
struct kmemleak_object *object;
struct prio_tree_node *node;
object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
if (!object) {
pr_warning("Cannot allocate a kmemleak_object structure\n");
kmemleak_disable();
return NULL;
}
INIT_LIST_HEAD(&object->object_list);
INIT_LIST_HEAD(&object->gray_list);
INIT_HLIST_HEAD(&object->area_list);
spin_lock_init(&object->lock);
atomic_set(&object->use_count, 1);
object->flags = OBJECT_ALLOCATED;
object->pointer = ptr;
object->size = size;
object->min_count = min_count;
object->count = 0; /* white color initially */
object->jiffies = jiffies;
object->checksum = 0;
/* task information */
if (in_irq()) {
object->pid = 0;
strncpy(object->comm, "hardirq", sizeof(object->comm));
} else if (in_softirq()) {
object->pid = 0;
strncpy(object->comm, "softirq", sizeof(object->comm));
} else {
object->pid = current->pid;
/*
* There is a small chance of a race with set_task_comm(),
* however using get_task_comm() here may cause locking
* dependency issues with current->alloc_lock. In the worst
* case, the command line is not correct.
*/
strncpy(object->comm, current->comm, sizeof(object->comm));
}
/* kernel backtrace */
object->trace_len = __save_stack_trace(object->trace);
INIT_PRIO_TREE_NODE(&object->tree_node);
object->tree_node.start = ptr;
object->tree_node.last = ptr + size - 1;
write_lock_irqsave(&kmemleak_lock, flags);
min_addr = min(min_addr, ptr);
max_addr = max(max_addr, ptr + size);
node = prio_tree_insert(&object_tree_root, &object->tree_node);
/*
* The code calling the kernel does not yet have the pointer to the
* memory block to be able to free it. However, we still hold the
* kmemleak_lock here in case parts of the kernel started freeing
* random memory blocks.
*/
if (node != &object->tree_node) {
kmemleak_stop("Cannot insert 0x%lx into the object search tree "
"(already existing)\n", ptr);
object = lookup_object(ptr, 1);
spin_lock(&object->lock);
dump_object_info(object);
spin_unlock(&object->lock);
goto out;
}
list_add_tail_rcu(&object->object_list, &object_list);
out:
write_unlock_irqrestore(&kmemleak_lock, flags);
return object;
}
/*
* Remove the metadata (struct kmemleak_object) for a memory block from the
* object_list and object_tree_root and decrement its use_count.
*/
static void __delete_object(struct kmemleak_object *object)
{
unsigned long flags;
write_lock_irqsave(&kmemleak_lock, flags);
prio_tree_remove(&object_tree_root, &object->tree_node);
list_del_rcu(&object->object_list);
write_unlock_irqrestore(&kmemleak_lock, flags);
WARN_ON(!(object->flags & OBJECT_ALLOCATED));
WARN_ON(atomic_read(&object->use_count) < 2);
/*
* Locking here also ensures that the corresponding memory block
* cannot be freed when it is being scanned.
*/
spin_lock_irqsave(&object->lock, flags);
object->flags &= ~OBJECT_ALLOCATED;
spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
}
/*
* Look up the metadata (struct kmemleak_object) corresponding to ptr and
* delete it.
*/
static void delete_object_full(unsigned long ptr)
{
struct kmemleak_object *object;
object = find_and_get_object(ptr, 0);
if (!object) {
#ifdef DEBUG
kmemleak_warn("Freeing unknown object at 0x%08lx\n",
ptr);
#endif
return;
}
__delete_object(object);
put_object(object);
}
/*
* Look up the metadata (struct kmemleak_object) corresponding to ptr and
* delete it. If the memory block is partially freed, the function may create
* additional metadata for the remaining parts of the block.
*/
static void delete_object_part(unsigned long ptr, size_t size)
{
struct kmemleak_object *object;
unsigned long start, end;
object = find_and_get_object(ptr, 1);
if (!object) {
#ifdef DEBUG
kmemleak_warn("Partially freeing unknown object at 0x%08lx "
"(size %zu)\n", ptr, size);
#endif
return;
}
__delete_object(object);
/*
* Create one or two objects that may result from the memory block
* split. Note that partial freeing is only done by free_bootmem() and
* this happens before kmemleak_init() is called. The path below is
* only executed during early log recording in kmemleak_init(), so
* GFP_KERNEL is enough.
*/
start = object->pointer;
end = object->pointer + object->size;
if (ptr > start)
create_object(start, ptr - start, object->min_count,
GFP_KERNEL);
if (ptr + size < end)
create_object(ptr + size, end - ptr - size, object->min_count,
GFP_KERNEL);
put_object(object);
}
static void __paint_it(struct kmemleak_object *object, int color)
{
object->min_count = color;
if (color == KMEMLEAK_BLACK)
object->flags |= OBJECT_NO_SCAN;
}
static void paint_it(struct kmemleak_object *object, int color)
{
unsigned long flags;
spin_lock_irqsave(&object->lock, flags);
__paint_it(object, color);
spin_unlock_irqrestore(&object->lock, flags);
}
static void paint_ptr(unsigned long ptr, int color)
{
struct kmemleak_object *object;
object = find_and_get_object(ptr, 0);
if (!object) {
kmemleak_warn("Trying to color unknown object "
"at 0x%08lx as %s\n", ptr,
(color == KMEMLEAK_GREY) ? "Grey" :
(color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
return;
}
paint_it(object, color);
put_object(object);
}
/*
* Mark an object permanently as gray-colored so that it can no longer be
* reported as a leak. This is used in general to mark a false positive.
*/
static void make_gray_object(unsigned long ptr)
{
paint_ptr(ptr, KMEMLEAK_GREY);
}
/*
* Mark the object as black-colored so that it is ignored from scans and
* reporting.
*/
static void make_black_object(unsigned long ptr)
{
paint_ptr(ptr, KMEMLEAK_BLACK);
}
/*
* Add a scanning area to the object. If at least one such area is added,
* kmemleak will only scan these ranges rather than the whole memory block.
*/
static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
{
unsigned long flags;
struct kmemleak_object *object;
struct kmemleak_scan_area *area;
object = find_and_get_object(ptr, 1);
if (!object) {
kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
ptr);
return;
}
area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
if (!area) {
pr_warning("Cannot allocate a scan area\n");
goto out;
}
spin_lock_irqsave(&object->lock, flags);
if (ptr + size > object->pointer + object->size) {
kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
dump_object_info(object);
kmem_cache_free(scan_area_cache, area);
goto out_unlock;
}
INIT_HLIST_NODE(&area->node);
area->start = ptr;
area->size = size;
hlist_add_head(&area->node, &object->area_list);
out_unlock:
spin_unlock_irqrestore(&object->lock, flags);
out:
put_object(object);
}
/*
* Set the OBJECT_NO_SCAN flag for the object corresponding to the give
* pointer. Such object will not be scanned by kmemleak but references to it
* are searched.
*/
static void object_no_scan(unsigned long ptr)
{
unsigned long flags;
struct kmemleak_object *object;
object = find_and_get_object(ptr, 0);
if (!object) {
kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
return;
}
spin_lock_irqsave(&object->lock, flags);
object->flags |= OBJECT_NO_SCAN;
spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
}
/*
* Log an early kmemleak_* call to the early_log buffer. These calls will be
* processed later once kmemleak is fully initialized.
*/
static void __init log_early(int op_type, const void *ptr, size_t size,
int min_count)
{
unsigned long flags;
struct early_log *log;
if (atomic_read(&kmemleak_error)) {
/* kmemleak stopped recording, just count the requests */
crt_early_log++;
return;
}
if (crt_early_log >= ARRAY_SIZE(early_log)) {
kmemleak_disable();
return;
}
/*
* There is no need for locking since the kernel is still in UP mode
* at this stage. Disabling the IRQs is enough.
*/
local_irq_save(flags);
log = &early_log[crt_early_log];
log->op_type = op_type;
log->ptr = ptr;
log->size = size;
log->min_count = min_count;
log->trace_len = __save_stack_trace(log->trace);
crt_early_log++;
local_irq_restore(flags);
}
/*
* Log an early allocated block and populate the stack trace.
*/
static void early_alloc(struct early_log *log)
{
struct kmemleak_object *object;
unsigned long flags;
int i;
if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
return;
/*
* RCU locking needed to ensure object is not freed via put_object().
*/
rcu_read_lock();
object = create_object((unsigned long)log->ptr, log->size,
log->min_count, GFP_ATOMIC);
if (!object)
goto out;
spin_lock_irqsave(&object->lock, flags);
for (i = 0; i < log->trace_len; i++)
object->trace[i] = log->trace[i];
object->trace_len = log->trace_len;
spin_unlock_irqrestore(&object->lock, flags);
out:
rcu_read_unlock();
}
/*
* Log an early allocated block and populate the stack trace.
*/
static void early_alloc_percpu(struct early_log *log)
{
unsigned int cpu;
const void __percpu *ptr = log->ptr;
for_each_possible_cpu(cpu) {
log->ptr = per_cpu_ptr(ptr, cpu);
early_alloc(log);
}
}
/**
* kmemleak_alloc - register a newly allocated object
* @ptr: pointer to beginning of the object
* @size: size of the object
* @min_count: minimum number of references to this object. If during memory
* scanning a number of references less than @min_count is found,
* the object is reported as a memory leak. If @min_count is 0,
* the object is never reported as a leak. If @min_count is -1,
* the object is ignored (not scanned and not reported as a leak)
* @gfp: kmalloc() flags used for kmemleak internal memory allocations
*
* This function is called from the kernel allocators when a new object
* (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
*/
void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
gfp_t gfp)
{
pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
create_object((unsigned long)ptr, size, min_count, gfp);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
}
EXPORT_SYMBOL_GPL(kmemleak_alloc);
/**
* kmemleak_alloc_percpu - register a newly allocated __percpu object
* @ptr: __percpu pointer to beginning of the object
* @size: size of the object
*
* This function is called from the kernel percpu allocator when a new object
* (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
* allocation.
*/
void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size)
{
unsigned int cpu;
pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
/*
* Percpu allocations are only scanned and not reported as leaks
* (min_count is set to 0).
*/
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
for_each_possible_cpu(cpu)
create_object((unsigned long)per_cpu_ptr(ptr, cpu),
size, 0, GFP_KERNEL);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
/**
* kmemleak_free - unregister a previously registered object
* @ptr: pointer to beginning of the object
*
* This function is called from the kernel allocators when an object (memory
* block) is freed (kmem_cache_free, kfree, vfree etc.).
*/
void __ref kmemleak_free(const void *ptr)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
delete_object_full((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_FREE, ptr, 0, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free);
/**
* kmemleak_free_part - partially unregister a previously registered object
* @ptr: pointer to the beginning or inside the object. This also
* represents the start of the range to be freed
* @size: size to be unregistered
*
* This function is called when only a part of a memory block is freed
* (usually from the bootmem allocator).
*/
void __ref kmemleak_free_part(const void *ptr, size_t size)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
delete_object_part((unsigned long)ptr, size);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free_part);
/**
* kmemleak_free_percpu - unregister a previously registered __percpu object
* @ptr: __percpu pointer to beginning of the object
*
* This function is called from the kernel percpu allocator when an object
* (memory block) is freed (free_percpu).
*/
void __ref kmemleak_free_percpu(const void __percpu *ptr)
{
unsigned int cpu;
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
for_each_possible_cpu(cpu)
delete_object_full((unsigned long)per_cpu_ptr(ptr,
cpu));
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
/**
* kmemleak_not_leak - mark an allocated object as false positive
* @ptr: pointer to beginning of the object
*
* Calling this function on an object will cause the memory block to no longer
* be reported as leak and always be scanned.
*/
void __ref kmemleak_not_leak(const void *ptr)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
make_gray_object((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
}
EXPORT_SYMBOL(kmemleak_not_leak);
/**
* kmemleak_ignore - ignore an allocated object
* @ptr: pointer to beginning of the object
*
* Calling this function on an object will cause the memory block to be
* ignored (not scanned and not reported as a leak). This is usually done when
* it is known that the corresponding block is not a leak and does not contain
* any references to other allocated memory blocks.
*/
void __ref kmemleak_ignore(const void *ptr)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
make_black_object((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
}
EXPORT_SYMBOL(kmemleak_ignore);
/**
* kmemleak_scan_area - limit the range to be scanned in an allocated object
* @ptr: pointer to beginning or inside the object. This also
* represents the start of the scan area
* @size: size of the scan area
* @gfp: kmalloc() flags used for kmemleak internal memory allocations
*
* This function is used when it is known that only certain parts of an object
* contain references to other objects. Kmemleak will only scan these areas
* reducing the number false negatives.
*/
void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && size && !IS_ERR(ptr))
add_scan_area((unsigned long)ptr, size, gfp);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
}
EXPORT_SYMBOL(kmemleak_scan_area);
/**
* kmemleak_no_scan - do not scan an allocated object
* @ptr: pointer to beginning of the object
*
* This function notifies kmemleak not to scan the given memory block. Useful
* in situations where it is known that the given object does not contain any
* references to other objects. Kmemleak will not scan such objects reducing
* the number of false negatives.
*/
void __ref kmemleak_no_scan(const void *ptr)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
object_no_scan((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
}
EXPORT_SYMBOL(kmemleak_no_scan);
/*
* Update an object's checksum and return true if it was modified.
*/
static bool update_checksum(struct kmemleak_object *object)
{
u32 old_csum = object->checksum;
if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
return false;
object->checksum = crc32(0, (void *)object->pointer, object->size);
return object->checksum != old_csum;
}
/*
* Memory scanning is a long process and it needs to be interruptable. This
* function checks whether such interrupt condition occurred.
*/
static int scan_should_stop(void)
{
if (!atomic_read(&kmemleak_enabled))
return 1;
/*
* This function may be called from either process or kthread context,
* hence the need to check for both stop conditions.
*/
if (current->mm)
return signal_pending(current);
else
return kthread_should_stop();
return 0;
}
/*
* Scan a memory block (exclusive range) for valid pointers and add those
* found to the gray list.
*/
static void scan_block(void *_start, void *_end,
struct kmemleak_object *scanned, int allow_resched)
{
unsigned long *ptr;
unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
unsigned long *end = _end - (BYTES_PER_POINTER - 1);
for (ptr = start; ptr < end; ptr++) {
struct kmemleak_object *object;
unsigned long flags;
unsigned long pointer;
if (allow_resched)
cond_resched();
if (scan_should_stop())
break;
/* don't scan uninitialized memory */
if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
BYTES_PER_POINTER))
continue;
pointer = *ptr;
object = find_and_get_object(pointer, 1);
if (!object)
continue;
if (object == scanned) {
/* self referenced, ignore */
put_object(object);
continue;
}
/*
* Avoid the lockdep recursive warning on object->lock being
* previously acquired in scan_object(). These locks are
* enclosed by scan_mutex.
*/
spin_lock_irqsave_nested(&object->lock, flags,
SINGLE_DEPTH_NESTING);
if (!color_white(object)) {
/* non-orphan, ignored or new */
spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
continue;
}
/*
* Increase the object's reference count (number of pointers
* to the memory block). If this count reaches the required
* minimum, the object's color will become gray and it will be
* added to the gray_list.
*/
object->count++;
if (color_gray(object)) {
list_add_tail(&object->gray_list, &gray_list);
spin_unlock_irqrestore(&object->lock, flags);
continue;
}
spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
}
}
/*
* Scan a memory block corresponding to a kmemleak_object. A condition is
* that object->use_count >= 1.
*/
static void scan_object(struct kmemleak_object *object)
{
struct kmemleak_scan_area *area;
struct hlist_node *elem;
unsigned long flags;
/*
* Once the object->lock is acquired, the corresponding memory block
* cannot be freed (the same lock is acquired in delete_object).
*/
spin_lock_irqsave(&object->lock, flags);
if (object->flags & OBJECT_NO_SCAN)
goto out;
if (!(object->flags & OBJECT_ALLOCATED))
/* already freed object */
goto out;
if (hlist_empty(&object->area_list)) {
void *start = (void *)object->pointer;
void *end = (void *)(object->pointer + object->size);
while (start < end && (object->flags & OBJECT_ALLOCATED) &&
!(object->flags & OBJECT_NO_SCAN)) {
scan_block(start, min(start + MAX_SCAN_SIZE, end),
object, 0);
start += MAX_SCAN_SIZE;
spin_unlock_irqrestore(&object->lock, flags);
cond_resched();
spin_lock_irqsave(&object->lock, flags);
}
} else
hlist_for_each_entry(area, elem, &object->area_list, node)
scan_block((void *)area->start,
(void *)(area->start + area->size),
object, 0);
out:
spin_unlock_irqrestore(&object->lock, flags);
}
/*
* Scan the objects already referenced (gray objects). More objects will be
* referenced and, if there are no memory leaks, all the objects are scanned.
*/
static void scan_gray_list(void)
{
struct kmemleak_object *object, *tmp;
/*
* The list traversal is safe for both tail additions and removals
* from inside the loop. The kmemleak objects cannot be freed from
* outside the loop because their use_count was incremented.
*/
object = list_entry(gray_list.next, typeof(*object), gray_list);
while (&object->gray_list != &gray_list) {
cond_resched();
/* may add new objects to the list */
if (!scan_should_stop())
scan_object(object);
tmp = list_entry(object->gray_list.next, typeof(*object),
gray_list);
/* remove the object from the list and release it */
list_del(&object->gray_list);
put_object(object);
object = tmp;
}
WARN_ON(!list_empty(&gray_list));
}
/*
* Scan data sections and all the referenced memory blocks allocated via the
* kernel's standard allocators. This function must be called with the
* scan_mutex held.
*/
static void kmemleak_scan(void)
{
unsigned long flags;
struct kmemleak_object *object;
int i;
int new_leaks = 0;
jiffies_last_scan = jiffies;
/* prepare the kmemleak_object's */
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
spin_lock_irqsave(&object->lock, flags);
#ifdef DEBUG
/*
* With a few exceptions there should be a maximum of
* 1 reference to any object at this point.
*/
if (atomic_read(&object->use_count) > 1) {
pr_debug("object->use_count = %d\n",
atomic_read(&object->use_count));
dump_object_info(object);
}
#endif
/* reset the reference count (whiten the object) */
object->count = 0;
if (color_gray(object) && get_object(object))
list_add_tail(&object->gray_list, &gray_list);
spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();
/* data/bss scanning */
scan_block(_sdata, _edata, NULL, 1);
scan_block(__bss_start, __bss_stop, NULL, 1);
#ifdef CONFIG_SMP
/* per-cpu sections scanning */
for_each_possible_cpu(i)
scan_block(__per_cpu_start + per_cpu_offset(i),
__per_cpu_end + per_cpu_offset(i), NULL, 1);
#endif
/*
* Struct page scanning for each node.
*/
lock_memory_hotplug();
for_each_online_node(i) {
pg_data_t *pgdat = NODE_DATA(i);
unsigned long start_pfn = pgdat->node_start_pfn;
unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
unsigned long pfn;
for (pfn = start_pfn; pfn < end_pfn; pfn++) {
struct page *page;
if (!pfn_valid(pfn))
continue;
page = pfn_to_page(pfn);
/* only scan if page is in use */
if (page_count(page) == 0)
continue;
scan_block(page, page + 1, NULL, 1);
}
}
unlock_memory_hotplug();
/*
* Scanning the task stacks (may introduce false negatives).
*/
if (kmemleak_stack_scan) {
struct task_struct *p, *g;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
scan_block(task_stack_page(p), task_stack_page(p) +
THREAD_SIZE, NULL, 0);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
}
/*
* Scan the objects already referenced from the sections scanned
* above.
*/
scan_gray_list();
/*
* Check for new or unreferenced objects modified since the previous
* scan and color them gray until the next scan.
*/
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
spin_lock_irqsave(&object->lock, flags);
if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
&& update_checksum(object) && get_object(object)) {
/* color it gray temporarily */
object->count = object->min_count;
list_add_tail(&object->gray_list, &gray_list);
}
spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();
/*
* Re-scan the gray list for modified unreferenced objects.
*/
scan_gray_list();
/*
* If scanning was stopped do not report any new unreferenced objects.
*/
if (scan_should_stop())
return;
/*
* Scanning result reporting.
*/
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
spin_lock_irqsave(&object->lock, flags);
if (unreferenced_object(object) &&
!(object->flags & OBJECT_REPORTED)) {
object->flags |= OBJECT_REPORTED;
new_leaks++;
}
spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();
if (new_leaks)
pr_info("%d new suspected memory leaks (see "
"/sys/kernel/debug/kmemleak)\n", new_leaks);
}
/*
* Thread function performing automatic memory scanning. Unreferenced objects
* at the end of a memory scan are reported but only the first time.
*/
static int kmemleak_scan_thread(void *arg)
{
static int first_run = 1;
pr_info("Automatic memory scanning thread started\n");
set_user_nice(current, 10);
/*
* Wait before the first scan to allow the system to fully initialize.
*/
if (first_run) {
first_run = 0;
ssleep(SECS_FIRST_SCAN);
}
while (!kthread_should_stop()) {
signed long timeout = jiffies_scan_wait;
mutex_lock(&scan_mutex);
kmemleak_scan();
mutex_unlock(&scan_mutex);
/* wait before the next scan */
while (timeout && !kthread_should_stop())
timeout = schedule_timeout_interruptible(timeout);
}
pr_info("Automatic memory scanning thread ended\n");
return 0;
}
/*
* Start the automatic memory scanning thread. This function must be called
* with the scan_mutex held.
*/
static void start_scan_thread(void)
{
if (scan_thread)
return;
scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
if (IS_ERR(scan_thread)) {
pr_warning("Failed to create the scan thread\n");
scan_thread = NULL;
}
}
/*
* Stop the automatic memory scanning thread. This function must be called
* with the scan_mutex held.
*/
static void stop_scan_thread(void)
{
if (scan_thread) {
kthread_stop(scan_thread);
scan_thread = NULL;
}
}
/*
* Iterate over the object_list and return the first valid object at or after
* the required position with its use_count incremented. The function triggers
* a memory scanning when the pos argument points to the first position.
*/
static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
{
struct kmemleak_object *object;
loff_t n = *pos;
int err;
err = mutex_lock_interruptible(&scan_mutex);
if (err < 0)
return ERR_PTR(err);
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
if (n-- > 0)
continue;
if (get_object(object))
goto out;
}
object = NULL;
out:
return object;
}
/*
* Return the next object in the object_list. The function decrements the
* use_count of the previous object and increases that of the next one.
*/
static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
struct kmemleak_object *prev_obj = v;
struct kmemleak_object *next_obj = NULL;
struct list_head *n = &prev_obj->object_list;
++(*pos);
list_for_each_continue_rcu(n, &object_list) {
struct kmemleak_object *obj =
list_entry(n, struct kmemleak_object, object_list);
if (get_object(obj)) {
next_obj = obj;
break;
}
}
put_object(prev_obj);
return next_obj;
}
/*
* Decrement the use_count of the last object required, if any.
*/
static void kmemleak_seq_stop(struct seq_file *seq, void *v)
{
if (!IS_ERR(v)) {
/*
* kmemleak_seq_start may return ERR_PTR if the scan_mutex
* waiting was interrupted, so only release it if !IS_ERR.
*/
rcu_read_unlock();
mutex_unlock(&scan_mutex);
if (v)
put_object(v);
}
}
/*
* Print the information for an unreferenced object to the seq file.
*/
static int kmemleak_seq_show(struct seq_file *seq, void *v)
{
struct kmemleak_object *object = v;
unsigned long flags;
spin_lock_irqsave(&object->lock, flags);
if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
print_unreferenced(seq, object);
spin_unlock_irqrestore(&object->lock, flags);
return 0;
}
static const struct seq_operations kmemleak_seq_ops = {
.start = kmemleak_seq_start,
.next = kmemleak_seq_next,
.stop = kmemleak_seq_stop,
.show = kmemleak_seq_show,
};
static int kmemleak_open(struct inode *inode, struct file *file)
{
return seq_open(file, &kmemleak_seq_ops);
}
static int kmemleak_release(struct inode *inode, struct file *file)
{
return seq_release(inode, file);
}
static int dump_str_object_info(const char *str)
{
unsigned long flags;
struct kmemleak_object *object;
unsigned long addr;
addr= simple_strtoul(str, NULL, 0);
object = find_and_get_object(addr, 0);
if (!object) {
pr_info("Unknown object at 0x%08lx\n", addr);
return -EINVAL;
}
spin_lock_irqsave(&object->lock, flags);
dump_object_info(object);
spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
return 0;
}
/*
* We use grey instead of black to ensure we can do future scans on the same
* objects. If we did not do future scans these black objects could
* potentially contain references to newly allocated objects in the future and
* we'd end up with false positives.
*/
static void kmemleak_clear(void)
{
struct kmemleak_object *object;
unsigned long flags;
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
spin_lock_irqsave(&object->lock, flags);
if ((object->flags & OBJECT_REPORTED) &&
unreferenced_object(object))
__paint_it(object, KMEMLEAK_GREY);
spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();
}
/*
* File write operation to configure kmemleak at run-time. The following
* commands can be written to the /sys/kernel/debug/kmemleak file:
* off - disable kmemleak (irreversible)
* stack=on - enable the task stacks scanning
* stack=off - disable the tasks stacks scanning
* scan=on - start the automatic memory scanning thread
* scan=off - stop the automatic memory scanning thread
* scan=... - set the automatic memory scanning period in seconds (0 to
* disable it)
* scan - trigger a memory scan
* clear - mark all current reported unreferenced kmemleak objects as
* grey to ignore printing them
* dump=... - dump information about the object found at the given address
*/
static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
size_t size, loff_t *ppos)
{
char buf[64];
int buf_size;
int ret;
if (!atomic_read(&kmemleak_enabled))
return -EBUSY;
buf_size = min(size, (sizeof(buf) - 1));
if (strncpy_from_user(buf, user_buf, buf_size) < 0)
return -EFAULT;
buf[buf_size] = 0;
ret = mutex_lock_interruptible(&scan_mutex);
if (ret < 0)
return ret;
if (strncmp(buf, "off", 3) == 0)
kmemleak_disable();
else if (strncmp(buf, "stack=on", 8) == 0)
kmemleak_stack_scan = 1;
else if (strncmp(buf, "stack=off", 9) == 0)
kmemleak_stack_scan = 0;
else if (strncmp(buf, "scan=on", 7) == 0)
start_scan_thread();
else if (strncmp(buf, "scan=off", 8) == 0)
stop_scan_thread();
else if (strncmp(buf, "scan=", 5) == 0) {
unsigned long secs;
ret = strict_strtoul(buf + 5, 0, &secs);
if (ret < 0)
goto out;
stop_scan_thread();
if (secs) {
jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
start_scan_thread();
}
} else if (strncmp(buf, "scan", 4) == 0)
kmemleak_scan();
else if (strncmp(buf, "clear", 5) == 0)
kmemleak_clear();
else if (strncmp(buf, "dump=", 5) == 0)
ret = dump_str_object_info(buf + 5);
else
ret = -EINVAL;
out:
mutex_unlock(&scan_mutex);
if (ret < 0)
return ret;
/* ignore the rest of the buffer, only one command at a time */
*ppos += size;
return size;
}
static const struct file_operations kmemleak_fops = {
.owner = THIS_MODULE,
.open = kmemleak_open,
.read = seq_read,
.write = kmemleak_write,
.llseek = seq_lseek,
.release = kmemleak_release,
};
/*
* Stop the memory scanning thread and free the kmemleak internal objects if
* no previous scan thread (otherwise, kmemleak may still have some useful
* information on memory leaks).
*/
static void kmemleak_do_cleanup(struct work_struct *work)
{
struct kmemleak_object *object;
bool cleanup = scan_thread == NULL;
mutex_lock(&scan_mutex);
stop_scan_thread();
if (cleanup) {
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list)
delete_object_full(object->pointer);
rcu_read_unlock();
}
mutex_unlock(&scan_mutex);
}
static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
/*
* Disable kmemleak. No memory allocation/freeing will be traced once this
* function is called. Disabling kmemleak is an irreversible operation.
*/
static void kmemleak_disable(void)
{
/* atomically check whether it was already invoked */
if (atomic_cmpxchg(&kmemleak_error, 0, 1))
return;
/* stop any memory operation tracing */
atomic_set(&kmemleak_enabled, 0);
/* check whether it is too early for a kernel thread */
if (atomic_read(&kmemleak_initialized))
schedule_work(&cleanup_work);
pr_info("Kernel memory leak detector disabled\n");
}
/*
* Allow boot-time kmemleak disabling (enabled by default).
*/
static int kmemleak_boot_config(char *str)
{
if (!str)
return -EINVAL;
if (strcmp(str, "off") == 0)
kmemleak_disable();
else if (strcmp(str, "on") == 0)
kmemleak_skip_disable = 1;
else
return -EINVAL;
return 0;
}
early_param("kmemleak", kmemleak_boot_config);
static void __init print_log_trace(struct early_log *log)
{
struct stack_trace trace;
trace.nr_entries = log->trace_len;
trace.entries = log->trace;
pr_notice("Early log backtrace:\n");
print_stack_trace(&trace, 2);
}
/*
* Kmemleak initialization.
*/
void __init kmemleak_init(void)
{
int i;
unsigned long flags;
#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
if (!kmemleak_skip_disable) {
atomic_set(&kmemleak_early_log, 0);
kmemleak_disable();
return;
}
#endif
jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
INIT_PRIO_TREE_ROOT(&object_tree_root);
if (crt_early_log >= ARRAY_SIZE(early_log))
pr_warning("Early log buffer exceeded (%d), please increase "
"DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
/* the kernel is still in UP mode, so disabling the IRQs is enough */
local_irq_save(flags);
atomic_set(&kmemleak_early_log, 0);
if (atomic_read(&kmemleak_error)) {
local_irq_restore(flags);
return;
} else
atomic_set(&kmemleak_enabled, 1);
local_irq_restore(flags);
/*
* This is the point where tracking allocations is safe. Automatic
* scanning is started during the late initcall. Add the early logged
* callbacks to the kmemleak infrastructure.
*/
for (i = 0; i < crt_early_log; i++) {
struct early_log *log = &early_log[i];
switch (log->op_type) {
case KMEMLEAK_ALLOC:
early_alloc(log);
break;
case KMEMLEAK_ALLOC_PERCPU:
early_alloc_percpu(log);
break;
case KMEMLEAK_FREE:
kmemleak_free(log->ptr);
break;
case KMEMLEAK_FREE_PART:
kmemleak_free_part(log->ptr, log->size);
break;
case KMEMLEAK_FREE_PERCPU:
kmemleak_free_percpu(log->ptr);
break;
case KMEMLEAK_NOT_LEAK:
kmemleak_not_leak(log->ptr);
break;
case KMEMLEAK_IGNORE:
kmemleak_ignore(log->ptr);
break;
case KMEMLEAK_SCAN_AREA:
kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
break;
case KMEMLEAK_NO_SCAN:
kmemleak_no_scan(log->ptr);
break;
default:
kmemleak_warn("Unknown early log operation: %d\n",
log->op_type);
}
if (atomic_read(&kmemleak_warning)) {
print_log_trace(log);
atomic_set(&kmemleak_warning, 0);
}
}
}
/*
* Late initialization function.
*/
static int __init kmemleak_late_init(void)
{
struct dentry *dentry;
atomic_set(&kmemleak_initialized, 1);
if (atomic_read(&kmemleak_error)) {
/*
* Some error occurred and kmemleak was disabled. There is a
* small chance that kmemleak_disable() was called immediately
* after setting kmemleak_initialized and we may end up with
* two clean-up threads but serialized by scan_mutex.
*/
schedule_work(&cleanup_work);
return -ENOMEM;
}
dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
&kmemleak_fops);
if (!dentry)
pr_warning("Failed to create the debugfs kmemleak file\n");
mutex_lock(&scan_mutex);
start_scan_thread();
mutex_unlock(&scan_mutex);
pr_info("Kernel memory leak detector initialized\n");
return 0;
}
late_initcall(kmemleak_late_init);
Jump to Line
Something went wrong with that request. Please try again.